An authorized counter example

1. We have a increment method in backend motoko code, which requires an non-anonymous identity to call.
2. We try to connect with internet identity to fetch user's identity.
3. If the identity is anonymous, the smart contract will return with error
4. If the identity is not anoymous, the smart contract will execute the actual increment.

• agent_dart
• agent_dart_auth
• internet identity(local or mainnet)
• middle page project(auth_client_demo)

1. agent_dart does not provide any UI related feature or components to keep itself clean as dart code.
2. agent_dart_auth uses an third-party plugin called flutter_web_auth to open up a WebView window to display the middle page.
3. middle page is used to redirect current authenticating request to internet identity, the reasons to do so are as folowing:
   1. internet identity ONLY accept browser request, it uses window and postMessage to complete the authentication flow. Thus third party apps like flutter or mobile apps can not pass parameters to it directly.
   2. Why don't we call its contract/canister directly? Because user keeps their II anchor number in their browsers, there's no way to extract those identities out of the browsers.
   3. The MOST IMPORTANT reason is that, when user authorize DApps on Mainnet, the II will calculate the delegation identity using DApps' url. If the url changes or use localhost, the delegation result will change. Thus we have to use a middle page to trick II we had our requests are from our DApps' webpage, which means you have to deploy at least one webpage to mainnet and to the same and stable auth url to II.
   4. The middle page is a very simple example that how do we complete the flow. There are still limitations:
      1. the project is coded by lit-html, if you are using React or Vue, you have to transpile yourself.
      2. THere are difference between android and ios in auto-redirecting. User have to click when web-to-flutter flow on Android, but flutter-to-web flow on iOS.

1. If you are tyring to use II, currently, no. Limitation is too much there.
2. AstroX is implementing our own identity service, which will link II as one of the identity providers. After we finish that part, we will make a flutter plugin to call smart-contract method directly, maybe without Webview popup.

Nikola from Distrikt.io, helped us to come up with the solution. sidc0des and RMCS from Canistore, helped us to debug latest agent-js dependencies and they complete the service worker for web. Solution and code will come after.